"Game of Thrones" fans should know by now not to get too attached to their favorite characters, but they might want to keep an eye on the rotating actors as well.

In the span of six seasons, several cast members have been replaced. Some of the characters are minor enough that fans probably missed the change, while others were slyly replaced with similar-looking actors.

From princes to mercenary soldiers, let's take a look at which "Game of Thrones" characters have reappeared with new faces.

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Princess Myrcella, sister to Joffrey, was originally played by Aimee Richardson in seasons one and two.

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Actress Nell Tiger Free took over for season five, when Myrcella was a little more grown up.

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Tommen Baratheon was also recast. Here's Callum Wharry as the youngest of Cersei's children in season one.

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Dean Charles Chapman took over starting in season four. The showrunners needed to age him up for a pending marriage consummation.

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This is what Gregor Clegane (The Mountain) looked like in season one when Conan Stevens played the brutish man.

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But he was recast in season two, and actor Ian Whyte took over briefly. The two look very similar.

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But then a third Gregor came along! Icelandic strongman Hafþór Júlíus Björnsson portrayed The Mountain in seasons three through six.

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David Michael Scott was originally cast to play Beric Dondarrion, a minor but important character in season one.

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Beric was offscreen for season two, but Richard Dormer returned as his incarnation in season three.

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Daario Naharis, the sellsword who seduced Daenerys, was played by Ed Skrein at the end of season three.

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The new Daario looked strikingly different when Michiel Huisman was recast. Fans were taken aback, but quickly grew used to his presence.

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Bloodraven — the magical tree-dweller Bran finally met in the season four finale — was originally played by Struan Rodger.

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Bloodraven and Bran were offscreen for all of season five. Max von Sydow was recast for the role in season six.

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Leaf — one of the Children of the Forest — was also introduced in the season four finale. Here's what she looked like when played by Octavia Selena Alexandru.

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But when Leaf turned up in season six, she had a whole new look. Kae Alexander was cast to play the magical and ancient character.

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This final example is one of the trickiest. In "Game of Thrones" season five, actor Richard Brake was given a lot of prosthetics to transform into the Night's King.

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Then, in season six, the same prosthetics were applied to new cast member Vladimir Furdik. The effect is the same, but you can tell there's a slightly different face under all the makeup.